A strip-shaped coaxial cone TSV and a preparation method thereof

Abstract

This invention provides a strip-shaped coaxial cone TSV and its fabrication method. The strip-shaped coaxial cone TSV includes multiple nested coaxial TSV functional layers. On a cross-section perpendicular to the axial direction of the strip-shaped coaxial cone TSV, each functional layer presents multiple nested elliptical strip-shaped racetrack structures with the same geometric center. From the outermost layer to the innermost layer, each coaxial TSV functional layer sequentially includes: an outer dielectric layer of a shielding ring, a shielding ring layer, an inner dielectric layer of the shielding ring, a benzocyclobutene layer, a silicon dioxide layer, and an internal metal filling layer. The strip-shaped coaxial cone TSV has an inverted isosceles trapezoidal shape, wider at the top and narrower at the bottom, in the main viewing direction. By integrating multiple nested coaxial TSV functional layers into a single strip structure, the chip area is significantly reduced. The combination of the coaxial TSV functional layers and the elliptical strip-shaped racetrack structure on the cross-section reduces leakage current and noise interference. Thus, the dual requirements of signal integrity and high integration for high-frequency applications are met.

Description

Technical Field

[0001] This invention relates to the field of three-dimensional integration and high-frequency interconnect technology, specifically to a strip-shaped coaxial cone TSV and its preparation method. Background Technology

[0002] With the rapid development of 3D integration technology, Through Silicon Vias (TSVs), as a core component for achieving high-speed interconnection between chips, have shown great potential in the Asia-Pacific Hertz band, especially for the miniaturization and high integration of high-frequency systems such as 6G communication. However, when the operating frequency is increased to the Asia-Pacific Hertz band, TSV structures face challenges such as signal crosstalk, noise interference, and increased transmission loss. To improve signal quality, existing solutions often adopt a signal-ground-signal transmission mode, but this mode requires multiple TSVs to work together, occupying a large chip area and limiting further improvements in system integration. Therefore, there is an urgent need for solutions that reduce area footprint while ensuring high-frequency performance.

[0003] In existing technologies, common TSV structures include cylindrical, conical, and ring-shaped TSVs. When applied to high-frequency transmission, these structures typically rely on the GSG pattern, where the central TSV is used for signal transmission, and grounded TSVs on both sides provide shielding to reduce crosstalk and noise. Furthermore, the coaxial TSV, as an improved structure, transmits signals through an internal conductor and achieves shielding through an external concentric metal ring grounded. It achieves a similar shielding effect to the GSG pattern using only a single TSV, thus offering advantages in area saving and becoming a more readily available solution.

[0004] However, the aforementioned existing technologies still have significant shortcomings. While GSG transmission mode can optimize signal quality to some extent, it requires a layout of at least three TSVs, significantly increasing chip area and hindering further reduction in device size, thus creating a bottleneck in integration. Although coaxial TSVs reduce area requirements, their shielding effect is limited in the ultra-high frequency band of the Asia-Pacific Hertz (APH), and signal transmission remains susceptible to leakage current and noise, leading to degraded transmission performance and failing to meet the dual requirements of signal integrity and integration for high-frequency applications. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a strip-shaped coaxial cone TSV and its preparation method.

[0006] The technical problem to be solved by this invention is achieved through the following technical solution: In a first aspect, the present invention provides a strip-shaped coaxial cone TSV, comprising multiple nested coaxial TSV functional layers; the coaxial TSV functional layers, on a cross-section perpendicular to the axis of the strip-shaped coaxial cone TSV, present as multiple nested elliptical strip-shaped track structures with the same geometric center; The coaxial TSV functional layer, from the outermost layer to the innermost layer, includes: an outer dielectric layer of the shielding ring, a shielding ring layer, an inner dielectric layer of the shielding ring, a benzocyclobutene layer, a silicon dioxide layer, and an internal metal filling layer. The strip-shaped coaxial cone TSV is an inverted isosceles trapezoid that is wider at the top and narrower at the bottom in the main viewing direction.

[0007] Optionally, the outer dielectric layer, the inner dielectric layer, and the silicon dioxide layer of the shielding ring are all made of SiO2 material, the shielding ring layer and the inner metal filling layer are both made of Cu material, and the benzocyclobutene layer is made of BCB material.

[0008] Optionally, the outer dielectric layer, the inner dielectric layer, and the silicon dioxide layer of the shielding ring have equal thicknesses.

[0009] Optionally, the height of the coaxial TSV functional layer is 100 μm.

[0010] Optionally, the width of the straight edge of the elliptical strip track structure corresponding to the internal metal filling layer is 7.85 μm.

[0011] Optionally, the diameter of the two semicircles at both ends of the elliptical strip track structure corresponding to the internal metal filling layer is 10 μm.

[0012] Optionally, the thickness of the silicon dioxide layer is 1 μm.

[0013] Optionally, the thickness of the benzocyclobutene layer is 3 μm, and the thickness of the shielding ring layer is 2 μm.

[0014] Optionally, the angle between the waist of the inverted isosceles trapezoid and the ground is 88°.

[0015] In a second aspect, the present invention provides a method for preparing a strip-shaped coaxial cone TSV, used to prepare the strip-shaped coaxial cone TSV of the first aspect described above, comprising: Etching silicon vias on a silicon substrate using Bosch technology; A first silicon dioxide layer is deposited in the silicon pores using a chemical vapor deposition method. The outer metal ring was deposited using a physical vapor deposition method. A second silicon dioxide layer was deposited using chemical vapor deposition. Thermally decomposed polymer filler; A third silicon dioxide layer was deposited using chemical vapor deposition. Inside the current silicon aperture, an inner layer metal is electroplated to fill it until it is completely filled.

[0016] This invention provides a strip-shaped coaxial cone TSV and its fabrication method. The strip-shaped coaxial cone TSV includes multiple nested coaxial TSV functional layers. On a cross-section perpendicular to the axial direction of the strip-shaped coaxial cone TSV, each coaxial TSV functional layer presents multiple nested elliptical strip-shaped racetrack structures with the same geometric center. From the outermost layer to the innermost layer, each coaxial TSV functional layer sequentially includes: an outer dielectric layer of a shielding ring, a shielding ring layer, an inner dielectric layer of a shielding ring, a benzocyclobutene layer, a silicon dioxide layer, and an internal metal filling layer. The strip-shaped coaxial cone TSV has an inverted isosceles trapezoidal shape, wider at the top and narrower at the bottom, in the main viewing direction. In this invention, by integrating multiple nested coaxial TSV functional layers into a single strip structure, the at least three independent TSV layouts required by the GSG mode are replaced, significantly reducing chip area and solving the problems of difficult device size reduction and integration bottlenecks. Then, the coaxial TSV functional layer in this invention includes a shielding ring layer and multiple dielectric layers. Combined with the elliptical strip racetrack structure on the cross-section, it enhances the electromagnetic shielding effect, reduces leakage current and noise interference, and solves the problem of signal transmission performance degradation in the Asia-Pacific Hertz ultra-high frequency band. Finally, the strip structure is an inverted isosceles trapezoid with a wider top and narrower bottom in the main view direction, which optimizes the impedance matching and transmission efficiency of the signal path, improves signal integrity, and meets the requirements of stable transmission for high-frequency applications. In summary, this invention, through nested functional layer integration, multi-layer shielding design, and inverted trapezoidal configuration, enhances shielding and signal transmission performance while reducing the area, thus satisfying the dual requirements of signal integrity and high integration in high-frequency applications.

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a strip-shaped coaxial cone TSV provided in an embodiment of the present invention; Figure 2 An exemplary schematic diagram of the strip coaxial cone TSV structure provided by the present invention in HFSS is shown; Figure 3 The S-parameter simulation results corresponding to the strip coaxial cone TSV provided by the present invention are shown as an example. Figure 4 This is a schematic flowchart illustrating a method for preparing a strip-shaped coaxial cone TSV according to an embodiment of the present invention. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0020] To meet the dual requirements of signal integrity and high integration in high-frequency applications, this invention provides a strip coaxial tapered TSV. Figure 1 This is a schematic diagram of a strip-shaped coaxial cone TSV provided in an embodiment of the present invention, as shown below. Figure 1 As shown, the strip-shaped coaxial cone TSV includes multiple nested coaxial TSV functional layers; the coaxial TSV functional layers, on the cross-section perpendicular to the axis of the strip-shaped coaxial cone TSV, present multiple nested elliptical strip-shaped runway structures with the same geometric center. The coaxial TSV functional layer, from the outermost layer to the innermost layer, includes: an outer dielectric layer 110 of the shielding ring, a shielding ring layer 120, an inner dielectric layer 130 of the shielding ring, a benzocyclobutene layer 140, a silicon dioxide layer 150, and an inner metal filling layer 160. The strip-shaped coaxial cone TSV is an inverted isosceles trapezoid that is wider at the top and narrower at the bottom in the main viewing direction.

[0021] It should be noted that in this invention, the outer dielectric layer 110, the shielding ring layer 120, the inner dielectric layer 130, the benzocyclobutene layer 140, the silicon dioxide layer 150, and the inner metal filling layer 160 present an elliptical strip racetrack structure in the vertical cross-section. This structure can increase the minimum distance between TSVs while keeping the center-to-center distance between TSVs unchanged, weakening the proximity effect and reducing crosstalk and coupling on the signal. While keeping the minimum distance between TSVs unchanged, this structure can reduce the center-to-center distance between TSVs, thereby reducing the device size and improving the system integration.

[0022] The specific analysis is as follows: First, the elliptical strip track structure provides a continuous and uniform shielding path. In the cross-section, each coaxial functional layer (especially the middle shielding ring layer) is a closed-loop conductor. This uninterrupted closed-loop structure effectively generates eddy currents, strongly canceling out external interference magnetic fields, thus isolating the internal signal conductor from external noise. Second, the elliptical strip track shape optimizes high-frequency current distribution. In the Asia-Pacific Hertz band, signal transmission exhibits a significant "skin effect," with current mainly concentrated on the conductor surface. The elliptical major and minor axis design, compared to a simple circle, provides a larger effective shielding perimeter within a limited area, increasing the surface area of ​​the shielding layer. This helps to carry a more uniform high-frequency shielding current, improving the absorption and reflection efficiency of high-frequency electromagnetic waves. Finally, the nested multi-layer structure achieves multiple shielding and impedance management. Multiple concentrically nested elliptical tracks constitute a multi-layered shielding system from the outside in. Each dielectric layer not only provides insulation but also works with the shielding layer to precisely control the characteristic impedance between layers. This design can gradually attenuate incoming noise and reduce interlayer signal reflection, thereby synergistically solving the problems of leakage current and noise interference.

[0023] like Figure 1As shown, the elliptical strip track structure in this embodiment of the invention includes two semicircles at the top and bottom and a rectangle in the middle. The diameter of the semicircles coincides with the lengths of the top and bottom two sides of the rectangle, which can be regarded as embedding a rectangle with a length equal to the diameter of the circle into a circular structure.

[0024] Optionally, the outer dielectric layer 110, the inner dielectric layer 130, and the silicon dioxide layer 150 of the shielding ring are all made of SiO2 material, the shielding ring layer 120 and the inner metal filling layer 160 are both made of Cu material, and the benzocyclobutene layer 140 is made of BCB material.

[0025] In this embodiment, the outer dielectric layer 110, the inner dielectric layer 130, and the silicon dioxide layer 150 of the shielding ring are used to prevent leakage current, the shielding ring layer 120 is used for noise shielding, and the inner metal filling layer 160 is used for signal transmission.

[0026] Optionally, the outer dielectric layer 110, the inner dielectric layer 130, and the silicon dioxide layer 150 of the shielding ring have equal thicknesses.

[0027] Optionally, the height of the coaxial TSV functional layer is 100 μm.

[0028] Optionally, the width of the straight edge of the elliptical strip track structure corresponding to the internal metal filling layer 160 is 7.85 μm.

[0029] Optionally, the diameter of the two semicircles at both ends of the elliptical strip track structure corresponding to the internal metal filling layer 160 is 10 μm.

[0030] Optionally, the thickness of the silicon dioxide layer 150 is 1 μm.

[0031] Optionally, the benzocyclobutene layer 140 has a thickness of 3 μm, and the shielding ring layer 120 has a thickness of 2 μm.

[0032] Optionally, the angle between the waist of the inverted isosceles trapezoid and the ground is 88°.

[0033] In addition, the strip coaxial cone TSV structure in this embodiment is cone-shaped as a whole, and in the main viewing direction, it is an inverted isosceles trapezoid with an upward opening. The angle between the waist of the inverted isosceles trapezoid and the ground is 88°. This angle can make the insulating layer of silicon dioxide material more uniform, improve the shielding effect on leakage current, and further reduce the high-frequency loss of the signal.

[0034] Specifically, the angle between the waist of the inverted isosceles trapezoid and the ground is set to 88° (nearly vertical but slightly tapered). The core purpose is to achieve an optimal balance between chip manufacturing process and high-frequency electrical performance. This near-vertical slight taper first ensures the feasibility and uniformity of the TSV structure in through-silicon via etching and subsequent metal filling processes, avoiding the process difficulties and reliability risks that might arise from completely vertical sidewalls. More importantly, from an electrical perspective, this carefully designed taper forms a gradual impedance transition region. As the signal travels from the wider top of the TSV to the narrower bottom, the equivalent capacitance and inductance along its path change smoothly, achieving continuous impedance matching and significantly reducing signal reflection and loss at abrupt changes in the transmission path (such as interfaces with upper and lower interconnects). This is crucial for signal integrity in the Asia-Pacific Hertz band, effectively suppressing noise and signal distortion caused by impedance mismatch, thus working in conjunction with the internal nested shielding layer to ensure high-quality transmission of high-frequency signals.

[0035] Furthermore, in order to verify the effectiveness of the strip coaxial cone TSV provided by the present invention, simulation experiments were also conducted.

[0036] Specifically, the strip-shaped coaxial cone TSV provided by this invention was modeled and simulated using the three-dimensional electromagnetic simulation software HFSS. First, the following parameters were set: the height of the coaxial TSV functional layer was 100 μm; the width of the straight side segment of the elliptical strip runway structure corresponding to the internal metal filling layer was 7.85 μm; the diameter of the two semicircles at both ends of the elliptical strip runway structure corresponding to the internal metal filling layer was 10 μm; the thickness of the silica layer was 1 μm; the thickness of the benzocyclobutene layer was 3 μm; the thickness of the shielding ring layer was 2 μm; and the angle between the waist of the inverted isosceles trapezoid and the ground was 88°. Based on these parameters, a simulation model of the TSV was established, adaptive boundary conditions and port excitations were applied, and the solution range was set to 0~180 GHz. After the simulation, the S-parameters of the strip-shaped coaxial cone TSV were obtained (S-parameters include: S11 - return loss parameter and S21 - insertion loss parameter). Figure 2 An exemplary schematic diagram of the strip coaxial cone TSV structure provided by the present invention in HFSS is shown. Figure 3 An illustrative example is shown of the S-parameter simulation results corresponding to the strip coaxial cone TSV provided by the present invention.

[0037] from Figure 3As can be seen, the S11 parameters of the strip coaxial cone TSV provided by this invention are -14.1dB, -8.76dB, and -6.17dB at 60, 120, and 180 GHz, respectively, and the S21 parameters are -0.188dB, -0.648dB, and -1.24dB, respectively. This indicates that the strip coaxial cone TSV can achieve signal transmission performance of S11 < -6dB and S21 > -1.25dB in the Asia-Pacific Hertz frequency range up to 180 GHz, verifying the effectiveness of the strip coaxial cone TSV provided by this invention.

[0038] Secondly, embodiments of the present invention also provide a method for preparing a strip-shaped coaxial cone TSV. Figure 4 This is a schematic flowchart of a method for preparing a strip-shaped coaxial cone TSV provided by an embodiment of the present invention, as shown below. Figure 4 As shown, it includes: S401, etching silicon vias on a silicon substrate using Bosch technology.

[0039] S402. A first silicon dioxide layer is deposited in the silicon pores using chemical vapor deposition.

[0040] S403, Deposit the outer metal ring using physical vapor deposition.

[0041] S404, a second silicon dioxide layer is deposited by chemical vapor deposition.

[0042] S405, Perform thermal decomposition polymer filling.

[0043] S406, a third silicon dioxide layer is deposited by chemical vapor deposition.

[0044] S407. Perform an electroplating filling process on the inner layer metal inside the current silicon hole until it is filled.

[0045] This invention provides a strip-shaped coaxial conical TSV, which integrates multiple nested coaxial TSV functional layers into a single strip structure, replacing the at least three independent TSV layouts required by the GSG mode. This significantly reduces chip area and solves the problems of limited device size and integration bottlenecks. Furthermore, the coaxial TSV functional layer in this invention includes a shielding ring layer and multiple dielectric layers. Combined with the elliptical strip racetrack structure on the cross-section, it enhances electromagnetic shielding, reduces leakage current and noise interference, and solves the problem of signal transmission performance degradation in the Asia-Pacific Hertz ultra-high frequency band. Finally, the strip structure has an inverted isosceles trapezoidal shape (wider at the top and narrower at the bottom) in the main viewing direction, optimizing impedance matching and transmission efficiency of the signal path, improving signal integrity, and meeting the stable transmission requirements of high-frequency applications. In summary, this invention, through nested functional layer integration, multi-layer shielding design, and inverted trapezoidal configuration, enhances shielding and signal transmission performance while reducing area, achieving the dual requirements of signal integrity and high integration in high-frequency applications.

[0046] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art, by reviewing the accompanying drawings and the disclosure, will understand and implement other variations of the disclosed embodiments in carrying out the claimed invention. In this description, the word "comprising" does not exclude other components or steps, "a" or "an" does not exclude a plurality, and "a plurality" means two or more, unless otherwise explicitly specified. Furthermore, while different embodiments may describe certain measures, this does not mean that these measures cannot be combined to produce good results.

[0047] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the inventive concept, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A strip-shaped coaxial cone TSV, characterized in that, It includes multiple nested coaxial TSV functional layers; the coaxial TSV functional layers, on a cross-section perpendicular to the axis of the strip coaxial cone TSV, present multiple nested elliptical strip track structures with the same geometric center; The coaxial TSV functional layer, from the outermost layer to the innermost layer, includes: an outer dielectric layer of the shielding ring, a shielding ring layer, an inner dielectric layer of the shielding ring, a benzocyclobutene layer, a silicon dioxide layer, and an internal metal filling layer. The strip-shaped coaxial cone TSV is an inverted isosceles trapezoid that is wider at the top and narrower at the bottom in the main viewing direction.

2. The strip-shaped coaxial cone TSV according to claim 1, characterized in that, The outer dielectric layer, the inner dielectric layer, and the silicon dioxide layer of the shielding ring are all made of SiO2 material, the shielding ring layer and the inner metal filling layer are both made of Cu material, and the benzocyclobutene layer is made of BCB material.

3. The strip-shaped coaxial cone TSV according to claim 1, characterized in that, The outer dielectric layer, the inner dielectric layer, and the silicon dioxide layer of the shielding ring have equal thicknesses.

4. The strip-shaped coaxial cone TSV according to claim 1, characterized in that, The height of the coaxial TSV functional layer is 100 μm.

5. The strip-shaped coaxial cone TSV according to claim 1, characterized in that, The width of the straight side of the elliptical strip track structure corresponding to the internal metal filling layer is 7.85 μm.

6. The strip-shaped coaxial cone TSV according to claim 1, characterized in that, The diameter of the two semicircles at both ends of the elliptical strip track structure corresponding to the internal metal filling layer is 10 μm.

7. The strip-shaped coaxial cone TSV according to claim 1, characterized in that, The thickness of the silicon dioxide layer is 1 μm.

8. The strip-shaped coaxial cone TSV according to claim 1, characterized in that, The thickness of the benzocyclobutene layer is 3 μm, and the thickness of the shielding ring layer is 2 μm.

9. The strip-shaped coaxial cone TSV according to claim 1, characterized in that, The angle between the waist of the inverted isosceles trapezoid and the ground is 88°.

10. A method for preparing a strip-shaped coaxial cone TSV, characterized in that, The preparation of the strip-shaped coaxial cone TSV according to any one of claims 1-9 comprises: Etching silicon vias on a silicon substrate using Bosch technology; A first silicon dioxide layer is deposited in the silicon pores using a chemical vapor deposition method. The outer metal ring was deposited using a physical vapor deposition method. A second silicon dioxide layer was deposited using chemical vapor deposition. Thermally decomposed polymer filler; A third silicon dioxide layer was deposited using chemical vapor deposition. Inside the current silicon aperture, an inner layer metal is electroplated to fill it until it is completely filled.

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